The present invention relates to a control apparatus and a control method of a variable valve timing mechanism that varies valve timing of engine valves (intake valve/exhaust valve) of an internal combustion engine.
Heretofore, there has been known a variable valve timing mechanism of an internal combustion engine in which a rotation phase of a camshaft with respect to a crankshaft is changed to vary valve timing of engine valves.
For example, in a variable valve timing mechanism disclosed in Japanese Unexamined Patent Publication No. 2001-041013, a driving rotor on a crankshaft side and a driven rotor on a camshaft side are coaxially connected to each other via a link type assembling angle adjusting mechanism.
Then, an assembling angle between the driving rotor and the driven rotor is changed by the assembling angle adjusting mechanism, to vary valve timing of engine valves.
However, in the variable valve timing mechanism described above, if a movable part is caught in a dent on a sliding contact portion surface of the assembling angle adjusting mechanism, a resistance to a change in the rotation phase becomes large, resulting in a fixed condition where the rotation phase cannot be changed by a normal control.
It is therefore an object of the present invention to provide a control apparatus and a control method of a variable valve timing mechanism, capable of resuming a change in a rotation phase even if a movable part is caught in a dent on a sliding contact portion surface of an assembling angle adjusting mechanism.
In order to accomplish the above-mentioned object, the present invention is constituted to forcibly drive an actuator in order to generate a torque alternately in an advance direction and a retarded direction of a rotation phase when a fixed condition of the rotation phase is detected.
The other objects and features of this invention will become understood from the following description with reference to the accompanying drawings.